


One Last Thing

by KazunaRei



Series: A Series of Things [3]
Category: Undertale (Video Game)
Genre: Anal Sex, Blow Jobs, Covers face and cries, Dies laughing forever, Don't have an heartattack over it, Ecto-Penis (Undertale), Ecto-Tongue (Undertale), I hope I did this well, M/M, Oral Sex, Reizumi is a cock whore, Reizumi wants the D again, Reizumi's asking problem continues, Sans gives him the D, Sans is forever patient, There's a bit of Japanese, Why Did I Write This?
Language: English
Status: Completed
Published: 2018-02-25
Updated: 2018-02-25
Packaged: 2019-03-23 17:04:34
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,036
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13792203
Author URL: https://archiveofourown.org/users/KazunaRei/pseuds/KazunaRei
Summary: Reizumi wants something again, so Sans puzzles it out.





	One Last Thing

**Author's Note:**

> Ok so here's something no one asked for but y'know I'm on a kick with this male story thing I guess. This is more than likely utter shit but take it anyway maybe you'll like it. o3o

Reizumi was at it once more. Had been for about two weeks, a new record for fretting, Sans thought wryly. What got him worked up now? The skeleton glanced at his human taking in the faint flush on his cheeks, the distant expression on his face; Reizumi picked at his fingers uncaring the he was pulling the skin away around his nails causing blood to well up. Sans took his hand gently making the dark-haired human blink back to awareness. “what’s wrong sweetheart?” 

“Ah,” His blush grew darker and he looked away brown eyes quivering. “It’s nothing . . .”

“you sure?” Reizumi’s first instinct was to deny anything was wrong, when clearly there was, Sans had been observing his actions for the past days. Obviously there was something he wanted. But was too embarrassed to ask, as always. The short skeleton tipped his skull thinking watching Reizumi stick his mildly bleeding thumb in his mouth sucking the blood away tongue flicking out. He had to look back at the TV before his magic ran south as he remembered his human’s warm warm mouth wrapped around his dick. And thinking of that caused a realization hit him. Sans knew what Reizumi wanted. Going beyond sucking him off.

He wanted to have sex.

His cheekbones tinted blue. In a way Reizumi was alot like Papyrus, the dark-haired male did things in stages. First with the kisses, he quite happily smothered Sans in kisses, now that he had free reign to do so. Papyrus always huffed good-naturedly that he had taken The Great Papyrus rightly deserved shower of kisses. But his brother was pleased by the affection Reizumi showed him. Always winking when the human pressed his lips anywhere on his skull or face.

And then oral sex, Reizumi still got flustered when he asked but the hesitance was gone. He happily got on his knees when permission was given, mouthing his cock reverently once it was presented and formed. He was fond of simply having Sans in mouth eyes half-lidded and glazed tongue fluttering gently sucking with barely any pressure. Reizumi admitted embarrassed sometime later that his magic was sweet and popped in his mouth leaving it tingling, a very pleasurable feeling he relished in.

So the next step between the two of them would be that. Sans glanced at his human again considering. Would Reizumi want to top him? Or would he prefer the skeleton too? Maybe that’s why he’s been so nervous and flighty, unsure about how the request would be taken. Whether Sans would want too, it was no secret between the two of them Sans was super lazy. Reizumi could be the same on a good day, but the short skeleton had him beat when it came to not expending effort. And there was a lot of effort expended in sex.

But whatever Reizumi wanted Sans gave, provided it was something reasonable.

Sex with his boyfriend was definitely reasonable.

Perhaps this time around he would take the initiative.

Sans reach out taking his human's hand away from his mouth, Reizumi had been worrying the thumb nail between his teeth, bright brown eyes blinked down at him. He let his grin grow wider eyelights glinting.

“so do you wanna bone me or let me bone you?”

Reizumi sputtered, stuck between laughter and trying to form words.

“Eh ha eh wah haha what-!”

“you wanna have sex sweetheart?” Now his face flushed bright red and he looked away off to the side.  

“I uh mm . . .” The human’s head dipped down bangs sliding forward around his glasses obscuring his eyes. He noted they flicked up at him through the wisps that swung before them. “You don't have to if-”

“come on, y'know i’d do anything for you.” The blush grew darker and Reizumi’s lips moved. Sans chuckled leaning forward. “say that again?” 

“Wo-would you take me?” The words were barely above a whisper spoke almost in a breathless puff of rushed air but he was looking at him tilting his head enough to meet the lights of his eyes.

“if that’s what you want.” Sans replied and found a kiss being pressed against his teeth. He was sure he felt a burst of happiness from the human. If it’s for Reizumi, Sans was willing to take the lead for once.

Even if it left him bone-tired in the end. Well Reizumi would let him sleep afterwards, provided Papyrus didn't come knocking, post-sex cuddles would be nice. Sans pulled back plucking the golden glasses off his human's face brushing the dark locks away threading his phalanges through his hair. Reizumi sighed leaning into the touch. “you want me to take you now?”

“Yes.” Reizumi looked off to the side shyly cheeks red. Sans grin softened into a smile. His human was so cute. He turned sliding across the couch crowding him back until he was sprawled on his back flushed anew.

“Saans not here!” Reizumi squeaked wide-eyed expression faintly horror filled.

“heh i know.” The skeleton crawled onto his human’s lap and they fell through a shortcut.

Sans hummed quietly pressing his teeth against Reizumi’s neck feeling him shiver caressing the soft warm skin lightly with brief kisses. The dark-haired human squirmed under him as he grazed his sides with just the tip of his phalanges magic sparking gently. Reizumi arched baring his neck breath hitching. Sans nipped at the newly exposed skin watching pleased as the milky tan flushed under the ministrations. Reizumi mewled softly and the skeleton felt a thrill through his being. Having Reizumi under him, hearing the sounds he made had pleasure curling in his soul.

He wondered dimly, sliding his hands under the shirt the human wore pushing it up to his shoulders, if this is how Reizumi felt when Sans was under him. Reveling in the bliss he caused as he pleasured the other. Reizumi always looked so pleased after Sans came. If so, the impending exhaustion would be worth it.

He hummed again against Reizumi’s neck feeling the shudder that racked his body and kissed his way down to his chest coming to a stop at a pink nipple dragging his conjured tongue over it. His human made a noise stuck between a moan and a squeak and clapped his hands over his mouth. Sans could feel the embarrassment rolling off him.

He chuckled drawing back reaching for his wrists uncovering the dark-haired human’s mouth. “hey that’s not fair. you get to hear all the embarrassing sounds i make, i want to hear you too.” The skeleton chided cheekbones puffed out in a mock pout. Reizumi blushed harder burying his face to the best of his ability in the shirt bunched around his neck.

“Muuh.  .  .”

“heh.” Sans huffed a laugh dipping his skull swiping his tongue over the nipple once more feeling it bud into a harden nub.

“Ah~.” Reizumi uttered a low moan wiggling and arching. Sans lamented his lack of lips, he’d like nothing more to suck on the peaked nipple under his tongue, but there was no helping it. The skeleton could bite it, gently of course, and proceeded to do so hand sliding away from the human’s wrist to his chest tweaking its twin to a similar harden state wringing louder moans from Reizumi. His human writhed beneath him breathing harshly in alternating pitches as he toyed with his chest switching sides giving both areas equal attention.

Then he was kissing down his middle lapping at the quivering flushed body leaving trails of wet magic tingling in his wake nipping here and there. Reizumi shook under him mewling and shifting hips rocking up. Sans felt something poking him; he slipped his phalanges under the shorts tugging them down along with his underwear. Reizumi always got excited so easily, he was leaving smears of precome on his skin cockhead shiny and wet another bead forming on the tip. The skeleton was half tempted to take him in, to create a soft lining of magic in his mouth and swallow, but moved downward with a trail of kisses around the member pulling the rest of his clothes down his legs tossing them off to the side.

He sunk his teeth into a thick thigh earning a keen from his human licking over the bite soothing the sting with a bit of magic. Reizumi panted heavily curling a hand in the blanket bunched under him. He was staring at the skeleton brown eyes glazed a deep flush of red on his cheeks. The human was shaking, body tremoring; Sans felt his thighs trembling under his hands. His face was full of desire. Reizumi was easy to please, but it was always a challenge to see the pleasure he felt. The human had a habit to hide his face when making expressions, to see his emotions plainly like this had his soul pulsing with delight.

Sans nuzzled his human's thigh rubbing the soft skin with his smooth cheekbone. The quivering grew worst Reizumi whined quietly legs moving restlessly closing in around him then sliding away. He chuckled slanting a leer from between his thighs eyelights flashing dragging his tongue around and up to his dripping cock curling lapping the fluid up. Reizumi uttered a cry head thrown back his hips twitched as he forced himself not to buck. Sans curled his hands over the squirming hips holding them in place magic gathering in his mouth forming a mock throat. The skeleton parted his teeth further sucking him in throat constricting magic vibrating.

A scream was his reward. Reizumi arched his hips might have smashed into the skeleton’s face if Sans hadn't braced himself keeping a tight grip on his human.

“Ah ah~!” He wailed writhing body shuddering head lolling against the pillow. He clawed at the blanket with one hand the other fisting the sheet. “MM nn~.”  His thighs clamped around his skull squeezing as he trailed off into hitched groans. “Saaans.”  

Reizumi twitched leaking in his mouth, Sans found himself swallowing greedily. The sourness mixed with his sweet magic made an appealing taste he savored on his undulating tongue. The skeleton bobbed his skull wanting more listening to Reizumi’s increasing cries and whines. Hearing him like this had his soul fluttering with pleasure. His human was usually so quiet, even when he got excited about things noises were muted muffled behind his hands while his eyes sparkled.

Sans had been mostly kidding with his earlier comment, but Reizumi took it to heart apparently letting out all his sounds.

All for his benefit.

Just for  _ him. _

Sans’ soul felt like it would burst from the rush of affection that rolled through his bones. His magic crested with the rising emotions flowing buzzing with excitement and Reizumi was screaming again spilling his mouth.

Sans drew back the dark-haired human’s essence lingering on his conjured tongue peering at him with half-lidded eyesockets. Reizumi gazed upward eyes glazed panting heavily flushed body shaking. He was hit with a pang of desire, his cock twitched in his shorts throbbing. The skeleton was sure the inside was a mess judging by the stickiness and how they clung to his formed magic. He shifted shimmying out them tossing the fabric off to the side feeling relieved at the lack of pressure on his pelvis.

Damn. Sans was so focused on pleasuring Reizumi he hadn't realized just how turned on he was. He was dripping magic on the blanket, thick dark blue drops showing how concentrated it was and how aroused he was.

“Hnng.” Reizumi’s soft keen made him look up.  His human’s eyes brightened at the sight of his dick. Pure unfiltered want came over his face.

A shiver went up his spine at the unadulterated expression. Reizumi was really holding nothing back, his magic pooled further south making him thicker. “you want this sweetheart?” He couldn't help but ask voice deepening to a rumble with his arousal curling his phalanges around his cock stroking causing more magic to drip. Sans stared enthralled as Reizumi shuddered.

“ _ Yes~.”  _ He sighed sitting up inky black hair falling in and around his face brushing rosy cheeks covering one lidded eye. “Please?” The sultry expression had him freezing heat pulsing from his soul. It was a running gag between their friends saying Reizumi’s emotional range was only a step up from a blank face robot. The human always grumbled he could emote, he just chose to emote when the situation called for it. But when he did, Reizumi was at his most attractive like right now. He was still long enough for Reizumi to reach for him tugging at the shirt he wore dragging him close until they were flush together. “Nn~ c’mon,” He rocked up against him with a soft moan. The friction had his eyelights rolling a groan rattling from his ribcage. It took everything he had not to rock back instead grabbing his human’s moving hips holding him still.

“Nyeh!” Reizumi made a sound of protest giving him an unhappy look that melted as he leaned up kissing his pouting lips.

“heh you wanted me to take you remember? can’t do that if i blow my load before i’m inside you, babe.” He scolded tutting with a grin. Though it was tempting to rut against him until they both came. Reizumi always looked best when there was blue on him . . .

“Mnn faster Sans.” Reizumi huffed interrupting the thought of his magic dripping off his body pulling back to grope at the side table by the bed. Fingers latched onto the drawer's handle tugging it open enough for him to stick his hand inside retrieving a small red container pressing it in his hand. Sans gave it a curious look. “You do know what to do, right?” He asked brows raised.

“course i do.” He dipped his skull dragging his tongue over his human’s neck relishing the shiver and quiet mewl. “relax and let me take care of you.” Sans peered up at him eyelights soft.

“Mm-hm . . .” Reizumi sighed laying back pliant beneath him legs parted.

Sans tickled the inside of his thigh making him squeak with the tips of his phalanges then twisted the top open glancing down at the clear contents. “Be careful with that,” Reizumi’s murmur made him look up. “I don’t want that oil all over my bed.”

“try not to kick around too much.” Sans placed the container off to the side within his reach phalanges dipping in the oil.

“Don't leave it on the bed,” The human huffed giving him a mildly exasperated glance. “We both know if it stays it  _ will  _ get knocked over.” He watched intently as the skeleton spread the oil over his fingers quaking in anticipation. “Or put the top back on when you’re done, then we can kick it.” He muttered almost like an afterthought.

Sans laughed giving him a soft fond look. Reizumi melted at the gentle expression cheeks glowing red and shook when he pressed one of his slick phalanges to his entrance rubbing. “Nnn~.” Reizumi moaned thighs falling further apart. Sans felt the puckered hole twitch, like it wanted to draw him in. He massaged the area making the surrounding skin wet before pushing in slowly.

Reizumi’s breathing hitched, stopping for a moment, and he breathed out shaky his walls squeezed his phalanx then loosened letting him slide further inside. Reizumi fluttered around him as he sunk in to his knuckle pausing. “you okay?”

“Mm ‘m fine,” The dark-haired human puffed out curling the sheet around his finger quickly gripping tight. “Keep moving . . .”

Sans eyed him intensive but obligingly drew back thrusting in once more. The next slides were easier as Reizumi got use to the feeling losing the tenseness in his body. His flush grew darker eyes hazing falling shut panting. The skeleton watched entranced losing himself in his human's reactions, the way he chewed his lip, the breathy gasps, his trembling body, and clenching opening soul humming in bliss. He was moving on autopilot pressing a second phalanx in with the first pushing through the tight ring.

“Kuh-!” Reizumi sucked in sharply eyes flying open. He froze the lights of his eyes going wide. “Don't don’t stop,” He was given a weak glare. “No matter what you do, this will hurt.” The human huffed biting his lip worrying it between his teeth. He was right of course; but even so, causing him pain was the last thing Sans wanted to do. “Keep moving please.” His human murmured when he was still for too long. Sans twisted sticking his free hand in the oil then curled his coated hand around Reizumi’s dick stroking.

He earned a choked moan. There was no stopping the pain as he stretched Reizumi open but at least he could distract him from it. He rubbed just under the head thrusting at the same time wringing a cry from his human. Reizumi bucked up in the grip around him and pushed down onto his phalanges keening as he curled them inside him. The dark-haired human’s walls clasped and fluttered clutching at his fingers. “Haa~.” Reizumi moaned lowly as the tip of his cock was rubbed tight hole growing loose as Sans spread him open. His body quickly adjusted and Sans paused just the tips still inside.

He was treated to a mild disapproving look through the arousal. Sans smiled sweetly, “just giving you a sec to brace yourself is all, no need to get all huffy.” He chuckled. Reizumi grumbled something that might have been an agreement or a protest words too breathy for him to understand rolling his hips down staring pointedly. He was being surprisingly impatient, a sign of his extreme want. Reizumi didn't mess around when he had a goal in mind and was set on something. The skeleton figured he should continue before his human got fed up, an irritated Reizumi was someone you didn't want to deal with. So he pushed a third phalanx in feeling the dark-haired male clench around them.

Reizumi whimpered squirming sucking the bottom lip into his mouth worrying it between his teeth. Sans held still waiting for him to adjust feeling the opening sporadically squeeze and quiver his other hand resuming its pumping on the human's dick. Reizumi’s body shuddered, “Mm ah~.” He rocked up into the motions gasping softly pressing down making his phalanges sink deeper inside. “Fuuah~.” Sans half tempted to tell him the slow down but the pleasure blooming on the human's face as he was stretched open moving faster him speechless. 

On the next drawback his tips just brushed a swell of flesh and Reizumi’s next gasp came out choked breath hitching. Sans’ eyelights lit up. He thrusted once more letting his phalanges drag over the spot, his human's walls constricted as he cried out arching. His soul thrummed happily radiating satisfaction he rubbed in firm circles spreading his fingers. Reizumi wailed body quaking. “AHH~!” Sans’ grin grew wider across his face. He indulged himself toying with the little spot stroking alternating softly and roughly listening to the dark brunet's pitched noises. He would have kept it up until Reizumi came but the human batted at the hand around his cock whining. No more teasing then.

He pulled his phalanges free. Reizumi whimpered at the lost hole clenching around nothing. Sans moved up his body brushing his teeth over the human's swollen lips cock head sliding against his entrance smearing magic on his skin. Reizumi’s hips tilted up he was murmuring quietly. It took the skeleton a second to realize the other was speaking Japanese, repeating a single word under his breath, one of the few he learned since becoming friends with the human.

Hayaku, which basically meant hurry.

So impatient. Sans thought amused and fond feeling a pike of pleaseness to have reduced the dark-haired male to speak his first language tongue flicking out over his human's lips and was immediately granted access their slick appendages twining together. Reizumi's arms came up wrapping around him wiggling down attempting to impale himself on the member pressed against him. Sans drew back curling a hand over the squirming hips holding him in place the other directing his dick the puckered hole rocking in. Reizumi uttered a low sound keening as he was filled. Sans gritted his teeth, the dark-haired male was squeezing tight walls clinging to his cock making it difficult to sink deep within. He huffed a groan slumping forward eyelights dilated.

“relax for me babe, making it real hard to move.” He sighed feeling pleasure curl up his spine. The human gripped tighter making him choke on a moan before loosening his breath hitching with stuttering mewls walls fluttering until the skeleton was hilted inside.

Sans shook magic rolling through his bones. His human's insides hotly constricting around him tore at his resistance. It took everything he had not to mindlessly rut into him, though Reizumi might like the sting of being stretched open like that.  The human was whispering in Japanese under his breath once more, a litany of words the monster barely knew that trailed off into a moan as he pulled back member dragging against his walls rubbing over that spot causing him to cry out arching. Sans dug his phalanges into the sheets panting harshly thrusting back in groaning as he sank into tight heat. Reizumi's legs wrapped around his hipbones pulling him closer until they were flushed together babbling in a mix of English and Japanese rocking to meet his thrusts. “Ah ii Sans~ more motto mm nn~.”  

Shiit. The skeleton thought delirious magic buzzing with his excitement and arousal his human's escalating cries echoing in skull. Reizumi angled his hips so each thrust stroked along the swell of flesh though the motions stuttered as he spasmed from the pleasure keening. Sans spat a curse finding himself moving faster adjusting the tilt of the human's hips striking that soft spot again and again grunting feeling him grow tighter. Reizumi clutched the back of his shirt tugging him up into a kiss sucking on his tongue grinding down.

Fuuuck. He moaned into the kiss squeezing his human's hip bucking up into him swallowing the choked gasps issuing from his mouth. God he was so close his magic felt fit to burst whirling winding tight. Reizumi pulled back from the kiss face flushed brown eyes cloudy black hair swing around his face expressed full of bliss. He was whispering again and it took the skeleton almost a minute to work out what was being said pass the pleasure filled trance he fallen into.

“Come in me~. Please please  _ in me. _ ”

Sans vision whited out. The rush left him dizzy mind spinning screaming into Reizumi's neck as he thrusted pace stuttering to completion. His human shrieked back bowing body seizing walls contracting around his dick milking more magic from his shuddering form. He trailed off into whimpering mewls going limp on the bed cuddling the skeleton close.

Sans’ eyesockets fell shut trying to catch his breath. Reizumi’s chest heaved under him heart thrumming trying to steady his breathing. He shifted and Reizumi's grip tightened around him at every point. He groaned at the squeezing on his cock still buried inside skull lolling on the human's shoulder. “sweetheart . . .”

“Nooh stay~.” Reizumi whined. Sans sighed going slack once more. They remained in place sprawled together until his magic deformed eliciting a unhappy protest from the human. Sans huffed a laugh pushing himself seeing the pout on the dark-haired male’s face.

“you really didn't think i would stay in you for the rest of the day.” The skeleton asked amused.

“You could have if you wanted too.”

“Reizumi please.” He quoted the human’s most used exasperated words.

“Meh.”

He chuckled shaking his skull, truly his human was something else. Sans lean forward brushing his teeth over the pouting lips being kissed in returned Reizumi's arms winding tighter around him. He pulled back face peppered with kisses. “Thank you.” Reizumi's bright brown eyes glittered with happiness. His teeth pulled up into a smile.

“you’re welcome of course.” His human all but radiated contentment face soft. His soul fluttered. “i love you.”

Reizumi blushed lips curving gently. “Love you too.”

**Author's Note:**

> By the way, I'm never writing smut again. 
> 
> (You shouldn't lie Kazzie. Don't you want to write that Papyrus story with Reizumi?) 
> 
> Shut up voice in my head! . . . 
> 
> Damnit.


End file.
